There are a number of different technologies for providing high bandwidth data communication services to customer premises (e.g., businesses and residences). One such approach is Fiber to the Home technology, which uses optical fibers to carry optical signals in an optical data network from a central office to customer premises. Wavelength Division Multiplexing Passive Optical Network (WDM PON) architectures that are based on Reflective Semiconductor Optical Amplifiers (RSOAs) or externally seeded Fabry Perot (FP) laser interferometers may be used in Fiber to the Home technology. One advantage of such WDM PON architectures is that they allow for providing colorless Optical Line Terminals (OLT) at a central office and colorless Optical Network Units (ONUs) at customer premises.
Both RSOAs and FP laser interferometers require a seeding source. For instance, sliced Broadband Light Sources (BLSs) are used in some implementations. In other implementations, a Wavelength Division Multiplexer (WDM) continuous wave (CW) laser comb is used. However, each of these approaches has drawbacks.
In approaches using a sliced BLS there are limitations on the channel count per light source and limitations on reach (e.g., distance of customer premises from a central office) and performance (e.g., speed and bit error rate). Approaches using WDM CW laser combs, while providing better performance in terms of speed, bit error rate, reach and channel count, are significantly more expensive than approaches using BLSs. The higher cost for WDM CW laser comb approaches is due, in part, to the cost of the WDM CW laser combs, which are relatively expensive, have only a single optical output and, therefore, each WDM CW laser comb delivers optical signals for only a single PON. Another cost concern with such an approach is the need to use low polarization dependent gain (PDG) devices to account for optical signal polarization in such approaches.